Sleep disorders are very common. The impact of these disorders on a person's long term health is unclear. The purpose of this project is to determine the cost to the health care system of patients with untreated sleep disorders and then to determine the change in cost with diagnosis and treatment. Hypotheses: Untreated sleep disorder patients (with sleep apnea, narcolepsy, and insomnia) are heavier consumers of health care services than age and sex matched controlled subjects and treatment will reduce these costs. Aims: The applicant will examine healthcare utilization data (and what patients were being treated for) of a large number of patients five years before diagnosis and five years after diagnosis and compare them to controls matched by age, gender, and postal code. The data will be obtained in a community with unrestricted access to medical care and where all the data is stored on a central database. To measure the use of medical services the applicant will analyze all doctors' claims and data from all hospitalization as well as use of prescription drugs. The applicant will establish whether treatment of these disorders reduces the consumption of healthcare services in these patients. The applicant expects to find fewer physicians visits, particularly for cardiovascular disease, neuro-psychiatric disease and general medical evaluations and for sleep apnea, fewer hospitalizations, particularly for cardiovascular disease and respiratory failure.